Railway traffic controlling apparatus



7 May 18, 1937. 7' P. H. CRAGO RAILWAY TRAFFIC CONTROLLING APPARATUS 2sheeis-sneet 1' Filed Aug. 19, 1936 o N35 was 1 g my? MQR *3, s25 us H15ATTORN EY .2 Sheets-sheaf, I

. QR @EI' V May 18, 1937. P. H. CRAGO RAILWAY TRAFFIC CONTROLLINGAPPARATUS Filed Aug. 1.9-, 1956 L N 3h 08 E II ll A 0B8 swfi EN $50 aw@N MEQQQ Y m Patented May 18, 1937 RAILWAY TRAFFIC CONTROLLING APPARATUSPaul H. Crago, Wilkinsburg, Pa., assignor to The Union Switch & SignalCompany, Swissvale, Pa., a, corporation of Pennsylvania ApplicationAugust 19, 1936, Serial No. 96,833

12 Claims.

My invention relates to railway trafiic controlling apparatus, andparticularly to apparatus operative to effect a warning cab signalindication upon approach to a permanent track hazard.

I will describe two forms of the apparatus embodying myinvention, andwill then point out the novel features thereof in claims. 7

In the accompanying drawings, Fig. 1 is a diagrammatic view of one formof apparatus embodying my invention, and Fig. 2 is a diagrammatic viewof a second form of apparatus which also embodies the invention. Fig. 3is a diagram illustrating an operating characteristic of the apparatusof Figs. 1 and 2.

,In each of the difierent views, like reference characters designatesimilar parts.

4 Referring to Fig. 1, a stretch of railway track over which trafficnormally moves in the direction indicated by an arrow is formed by theusual insulated rail joints intosuccessive track sections, only theadjacent ends of two sections IT and 2T being shown in the drawings forthe sake of simplicity. That is, only one signal location A is shown inFig. l and it will be understood that each junction of adjacent sectionsconstitutes a signal location similar tolocation A. This stretch ofrailway is provided with a trackway apparatus necessary for a combinedwayside and cab signal system, the cab signal system being of the codetype. The apparatus for this combined wayside and cab signal system ispreferably that in general use and will be described in the presentapplication only insofar as is necessary for a full understanding of myinvention. As here shown, the apparatus is that necessary to effectivelyoperate a cab signal capable of displaying clear, approach, slow, andstop indications; and to eifectively operate a wayside signal capable ofdisplaying clear, approach, and stop indications. The train carriedequipment for a cab signal system of the type here contemplated may bethat disclosed and claimedin the United States Letters Patent No.1,773,472, granted August 19, 1930, to P. N. Bossart, for Railwaytraffic controlling apparatus, and to which patent ref- Each tracksection of the system is provided with a track circuit consisting of asource of current connected across the rails. at the exit end of thesection anda track relay connected across the rails at the entrance ofthe section. Hence, the source of current for the track cir- 5 cuit ofsection IT and the track relay for the track circuit of section 2T arelocated at the signal location A. The immediate source of current forthe track circuit of section IT is the secondary winding 2 of a tracktransformer TI, the primary winding 3 of which is at times supplied withnoncoded alternating current and at other times with coded alternatingcurrent as will appear hereinafter.

In a combined wayside and cab signal system of the type here involvedtwo independent sources of alternating current are commonly provided. Ashere shown, the secondary winding I of a line transformer TLI is asource of cycle alternating current by virtue of the primary winding 8of that transformer being connected with a 60 cycle alternating currentgenerator not shown. The secondary winding 9 of a line transformer TL2is a source of cycle alternating current by virtue of the primarywinding I0 of trans- 25 former TL2 being connected with a 100 cyclealternating current generator notshown. The secondary winding 1 of linetransformer TLI is connected across two bus bars BX and GK, and oneterminal of secondary winding 9 of transformer TL2 is connected directlywith bus bar CX over wire 42 and its other terminal is connected with acircuit network to be described later. The 60 cycle alternating currentis used for energizing the track circuit under normal conditions, thatis, when the track section is unoc-, cupied, and to operate the waysidesignal system. The 100 cycle alternating current is coded and is used toinfluence the train carried cab signal equipment in the manner describedin the aforementioned Bossart patent. One terminal of primary winding 3of track transformer TI is connected over wire I2 with the OK bus barand the other terminal of winding 3 is connected with bus bar BX overwire I3, front contact ll of a relay 2V to be referred to later, andwire I5. It follows that at such time as relay 2V is energized and itsfront contact I4 is closed, non-coded 60 cycle alternating current issupplied to the track rails of section IT, but that entry of a traininto section IT to shunt the track relay of that section and cause therelay 2V to be deenergized in a manner to shortly appear, the supply of60 cycle alternating current to the rails of section IT is discontinued.The code selection 55 circuit network by which secondary winding 9 ofline transformer TL2 is at times connected with the primary winding 3 oftrack transformer TI for supplying coded alternating current to therails of section IT will be described later. It will be understood, ofcourse, that alternating current of a single frequency may be used forboth the wayside and cab signal equipments.

The track relay 2TB, for the track circuit of section 2T is a twoelement alternating current relay responsive to 60 cycle alternatingcurrent. An approach relay 2V and a line relay 2SA are provided atlocation A. Relay 2V is governed over a line circuit including line wire4 extending to the location in the rear of location A and at which rearlocation it is connected to the-60 cycle alternating current source inthe same manner that line wire 5 leading to the V relay at the locationin advance of location A is connected over front contact 6 of trackrelay ZITR, with the 60 cycle alternating current source at location A.Thus,-relay 2V is normally energized by current supplied fromthelocation in the rear of location A- and is deenergized in response toa train entering section lT and shunting thetrack relay of e thatsection. The line relay 2SA is governed over a line circuit (not shown)responsive to traffic conditions in advance of section 2T. This linecircuit would be in accordance with standard practice. Consequently,under clear traffic conditions in advance of location A and whichpermits high train speeds through section 2T, both track relay 2TB andline relay 2SA are picked up; under approach trailic conditions thatrequire a speed restriction, track relay 2TB, is picked up and linerelay ZSA is down; and when section 2T is occupied, -track relay 2TB, isreleased.

The apparatus at location A also includes a code transmitter CT. Thetype of code transmitter is immaterial, and, as here shown, theoperating winding I6 thereof is supplied with current from anyconvenient source, such as the BXCX bus bars, over a simple circuitincluding back contact I! of relay 2V. The code transmitter CT operatesthree coding contact members 80, I20, and ISO the arrangement beingsuchthat coding contact member 80 is operated between two stationarycontacts I8 and I9 at the rate of 80 times per minute, contact memberI20 is operated between twostationary contacts 20 and 2I at the rate of120 times per minute, and contact member I80 is operated between twostationary contacts 22 and 23 at the rate of 180 times per minute. Itfollows that the code transmitter CT is normally inactive and isenergized and rendered active to operate its code contact members inresponse to a train entering section IT and shunting the track relay ofthat section to cause relay 2V to be deenergized. As pointed outhereinbefore, the supply of non-coded 60 cycle alternating current isremoved from the primary winding 3 of track transformer TI when relayjZVis released and its front contact I4 is opened. In the event of cleartraffic conditions in advance of location A andrelays 2TR and 23A areboth, picked up when relay 2V is released, 100 cycle alternating currentcoded at the 180 code is supplied to primary winding 3, and hence issupplied to the track rails of section IT where it is efiective toestablish a clear cab signal indication for the train carried equipmentof the train the entry of which into section IT causes the release ofrelay 2V. This 180 code selection circuit may be traced from therighthand terminal of primary winding 9 over back contact35 of relay2V,wire 3Ii,*contact 22, code contact member I80, Wire 31, a circuitnetwork to be later described in detail to wire 38, thence over frontcontacts 39 and 40 of relays 28A and 2TB, respectively, wires 4| and I3,primary winding 3 of track transformer TI, wire I2 to bus bar GK, andwire 42 to the left-hand terminal of primary winding 9. In the event ofapproach trafflc conditions in advance of location A and relay 2TB ispicked up and relay ZSA is released when relay 2V is deenergized, 100cycle alternating current of the 120 code is supplied to the primarywinding 3 of track transformer TI to effect the approach indication ofthe cab signal. The 120 code selection circuit includes secondarywinding 9, back contact 35 of relay 2V, wire 36, contact 20, codecontact member I20, wires 43 and 44, back contact 45 of relay 2SA, frontcontact 40 of track relay 2TR,-and thence as previously traced forthe-180 code selection circuit. Again, if the section 2T is occupied andtrack relay ZTR is down when the relay 2V isreleased, 100 cyclealternating current coded'at' the 80 code is supplied to the primarywinding 3 of track trans-' former TI to effect the display of a slow cabsignal. The 80 code selection circuit extends from secondary winding 9over back contact 35, "wire 36, contact I8, code contact member-Bfl,wire-46, back contact 41 of re1ay"2'I'R,, and thence as previouslytraced. In the case the tracksection 2T is occupied by a preceding trainand rail current is shunted by the wheels and axles of the precedingtrain the cab signal equipment of a following train entering section 2Tis deenergized to effect the display of the stop cab signal. Itis to benoted that by means of the contacts I9, 2|, and 23 of the codetransmitter'CT, impulses-of'fiO cycle alternating current are suppliedto thetrack rails of section IT during each off period of'the coded 100cycle alternating current, and hence-the track relay of section IT iseffectively energized and picked up immediately following the vacatingof that section.

The apparatus thus far described is that necessary for a combinedWayside and cab signal system in general use except for the circuitnetwork interposed in the 180 code selection circuit and which networkis controlled by apparatus embodying my invention. It will beunderstood. of course, thateach signal location of the system isprovided with apparatus similar-tothat described for location A exceptthe apparatus embodying my invention and which latter apparatus would beadded at selected points as desired.

As shown in the right-hand end of Fig.1, the stretch of railway trackincludes a'permanent track hazard at which a relatively low train speedis required for safety. Such track'h'azard may be, for example, a curve."It isthere'fore desirable to warn enginemen of trains approaching suchtrack hazard in addition to the usual rules governing speeds over theterritory. That a distinctive warning indication of the cab signal maybe established as a train-enters the section IT to the rear of thesection 2T'in which-the track hazard exists, I provide additionalapparatus that includes four relays"TA,TB,TC, and TD. These relays arepreferably direct current neutral relays, relaysTA, TB, and TC beingslow release and slow pickup in character, and relay TD being ofthe'ordinary acting type. The slow release and slow pickup periodsdfrelays TA, TB, and TC may be selected as desired and I shall assumefor thepurpose'of illustrating the operation of the apparatus embodying-my' invention that the release period of each of the relays is 2seconds and that the pickup period of each of these relays is 2 seconds.It has been found that direct current relays of this type can beproportioned and adjusted to provide a 2 second pickup period and a 2second release period when the relay is of the usual construction. Inthe drawings" certain of the relay contact fingers are shown remote fromthe winding of the relay for the sake of simplicity. In each suchinstances the contact finger is given a reference charactercorresponding to the reference character of the relay plus a distinctivenumeral, and each is shown in the position corresponding to the positionof the relay.

Relay TA is normally energized over a circuit extending from the Bterminalof any convenient source of direct current such as a battery notshown, front contact 24 of relay 2V, wire 25, winding of relay TA and tothe C terminal of the same source of current. Relay TA may also beenergized over either one of two branch paths one of which includes backcontact T026 and the other of which includes front contact TDZI. Theenergizing circuit for relay TB includes back contact 28 of relay TA,and the energizing circuit of relay TC includes the back contact 29 ofrelay TB. Relay TD is provided with a pickup circuit including batteryterminal B, front contact TA3ll, back contact TB3I, back contact 32 ofrelay TC, winding of relay TD, and to the C terminal; and'it is alsoprovided with a stick circuit including back contact 2V33 as well as itsown front contact 34. Thus under normal conditions, that is, when tracksection IT is unoccupied and relay 2V is energized, relays TA and T0 arepicked up and relays TB and TD are released.

The control of the coding means including the code transmitter CT andthe associated code selection circuit network is modified by theoperation of relays TA, TB, TC, and TD when a. train enters section ITunder clear traffic conditions-and high train speed is permitted, and adistinctive indication'of the cab signal is effected to warn theengineman of the approach to the permanent track hazard. This operationis as follows: As set forth hereinbefo-re, cycle alternating current of180 code is ordinarily supplied to the track rails of a section underclear traffic conditions to effect a clear indication of the cab signal.In accordance with my invention, two interruptions of the 180 codecurrent of predetermined fixed intervals are effected, these twointervalsbeing separated by another interval of like duration in which180 code current is supplied. During the two intervals the 180 codecurrent is interrupted, current of the code is supplied and the approachcab signal indication is established. These two intervals during which120 code current is supplied and the interval separating these twointervals are each 4 seconds in duration on the assumption that thepickup and release periods of relays TA, TB, and TC are 2 seconds each,since the release period of one relay and the pickup period of a secondrelay are combined in each case to form an interval. This operation isillustrated in Fig. 3. Looking at Fig. 3, during the first 4 secondperiod subsequent to entry of a train into section IT under cleartraffic conditions, 120 code current is supplied to the track rails ofthe section, during the second 4 second period code current is supplied,during the third 4 second period 120 code current is supplied, and thenthis is followed by current of 180 code. Hence,

during the first 4 seconds, an approach cab signal is displayed, duringthe second 4 seconds a clear cab signal is displayed, during the third 4seconds the approach cabsignal is again displayed, and this is thenfollowed by the display of theclear cab signal as long as the train 0c.-cupies the section, assuming, of course, that the clear trafiicconditions continue to exist.

When the train enters the section IT and relay 2V is released, the firstcode circuit selection available can be traced from the secondarywinding 9 of transformer TL2 over back contact 35 of relay 2V, wire 36,contact 20, code contact member I20, wire 43, back contact 48 of relay2V, back contact TB49, back contact T1350, front contact TC5I, wire 38,front contacts 39 and 40 of relays ZSA and 2TH, respectively, wires Mand I3, primary winding 3 of track transformer TI, wire I2, bus bar GK,and wire 42 back to the opposite terminal of secondary winding 9'.

Release of relay 2V to open front contact 24 deenergizes relay TA andthat relay is released at the end of its release period to. close backcontact 28 and energize relay TB which relay picks up at the end of itspickup period. When relay TB picks up, the above traced code selectioncircuit for supplying 120 code current is opened at back contact T349.With relay TA down and relay TB up, a new code selection circuit iscompleted and current of 180 code is supplied to the trackrails ofsection IT. This 180 code selection circuit may be traced from secondarywinding 9 over back contact 35, wire 36, contact 22, codecontact memberI 80, wire 31, front contact TB52, back contact TA53, wire 38, andthence as previously traced. With relay TB picked up and its backcontact 29 opened, the relay TC is deenergized and releases at the endof its release period; and with relay TC down and back contact T026closed, the relay TA is energized and picks up at the end of its pickupperiod. Consequently at the end of the next 4 second period, the lasttraced code selection circuit is opened at the back contact -TA53. Withrelay TC down and relay TA up, a new code selection circuit'is formedwhich extends from primary winding 9 over the elements ,35, 36, 20, I20,43 and 48, back contact TCM, front contact TA53, wire 38, and thence aspreviously traced, and 120 code current is supplied to the section IT.With relay TA picked up, the relay TB is deenergized and releases at theexpiration of its release period closing back contact 29 andenergizingthe relay TC which picks up at the end of its pickup period. During theinterval relay TB is down and relay TC has not yet picked up, the relayTD is energized over its pickup circuit which includes front contactTA30, back contact TB3I, and the back contact 32 of relay TC. Relay TDonce picked up I is then retained energized over its stick circuitincluding back contact 2V33. Thus at the end of the third 4 secondperiod, the last traced code selection circuit for supplying 120 codecurrent is opened at the back contact T054 and a new code.

selection circuit is completed for supplying current of 180 code. Thisconnection extends from primary winding 9 over the elements 35, 36, 22and I89 to'wire 31, and thence over front contact TDEEI, front contactTC5I, wire 38 and as previously traced, and this circuit is retainedclosed until the train vacates the section IT and the relay 2V isreenergized. Further operation of the relays TA, TB, and TC ispreventedsince the relay TA is retained energized over front contact TDZI whichlatter relay is held energized over its stick circuit. When the trainvacates section IT and relayZV. is picked up, the relay is deenergizedand at once releases to assume its normal deenergized position. It is tobe noted that in the event approach or slow traffic conditions exist inadvance of section IT and relay 2SA is deenergized, or both relays 2TH,and 2SA are deenergized, the relays TA, TB,'and TC are ineffective tocontrol the code selection connection.

In Fig. 2, the apparatus for the combined wayside and'cab signalsystemis the same as in Fig. 1 and it is thought to be unnecessary to repeatits description. The relays TA, TB, TC, and TD are also the same as inFig. 1. A direct current relay TF of the ordinary acting type is addedand the code selection circuit is carried over contacts of this. relayTF. It has been found that ordinary acting relays are more satisfactorythan slow acting relays for opening and closing the inductive loadsinvolved in coded track circuits. When a train enters section IT of Fig.2 and causes relay 2V to be released, the first code selection circuitincludes secondary winding 9, back contact 35 of relay 2V, wire 36, codecontact member l2il, wire 43, back contact 55 of relay TF, wire 38,front contacts 39 and 40 of relays 2SA and 2TB, respectively, wires 4|and I3, primary winding 3, wire I2, bus bar GK, and wire 42 to thesecondary winding 9. In the first 4 second period, subsequent to therelease of relay 2V, relay TA is released and relay TB is picked up inthe manner described in Fig. 1. With relay TA down and relay TB up, therelay TB is picked up over a circuit including front contact TB56 andback contact TAB'I. Thus at the end of the first 4 second period, relayTF picks up and opens the first code selection circuit at back contact55 and closes a new code selection circuit at front contact 58 overwhich current of the 180 code is supplied as will readily be understoodby an inspection of Fig. 2. At the end of the second l second period,relay TC is released and relay TA. is picked up. Relay TA on picking upopens the circuit for relay TF at back contact TA5'I and relay TF is atonce released to switch the code selection circuit back to the circuitfor supplying the 120 code current. During the third 4 second period,relay TB is released and relay TC is again picked up, relay TD beingalso picked up during this period and then retained energized over itsstick circuit in the manner described in Fig. 1. Relay TF is nowenergized over front contact TC59 and front contact TDGD and the codeselection circuit is switched back to the 180 code circuit. Since relayTD is retained energized over its stick circuit until the relay 2V isreenergized, further operation of the relays TA, TB, and TC is preventedand current of the 180 code is supplied to the section I T as long asthe train occupies that section. It is clear, therefore, that theapparatus of Fig. 2 is operative to: cause a distinctive warningindication of the cab signal to be displayed subsequent to thetrainentering the section lT to warn the engineman of approach to'thepermanent track hazard encountered in section 2T.

Although I have herein shown and described only two forms of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: a

1. In combination, a railway track formed into insulated track sections,coding means operative 75 at times .tosupply coded .current ofafirstcode to the rails of a section under clear trafiic conditions in advanceand to supply coded current of a second code to the rails of the sectionunder approach traffic conditions in advance, and means controlled by atrain upon entry into the section under clear trafiic conditions tomodify the operation of the coding means to supply current of the secondcode to the rails for at least one short definite period before currentof the first code is supplied to the rails.

2. In combination, a railway track formed into insulated track sections,coding means operative at times. to supply coded current of a first codeto the rails of a section under trafiic conditions which permit arelatively high train speed and insulated track sections, coding meansoperative at times to supply coded current'of a firstcode to the railsof a section under clear trafiic conditions in advance and to supplycoded current of a second code to the rails of the section underapproach trafiic conditions in advance, and means controlled by a trainupon entry. into the section under clear trafiic conditions to modifythe operation of the-coding means to supply currentof the second codefor a first short definite period followed by current of the first codefor a second short definite period followed by current of the secondcode for a third short definite period and this followed by anuninterrupted period of current of the first code.

4. In combination, a railway track formedinto insulated track sections,coding means operative at times to supply to the rails of a sectioncurrent coded at a first code or at a second code according to a firstor a second traffic condition in advance of the section, and meanscontrolled by a train upon entry into the section under the firsttralfic conditions to modify the operation of the coding means andsupply current of the second code and first code alternately for atleast three short definite periods and then supply current of the firstcode as long as the train occupies the section and the first trafiicconditions continue to exist.

5. In combination, a stretch of railway track including a permanenttrack hazard formed into insulated track sections, coding meansoperative at times to supply coded current of a first code to the railsof a section under traffic conditions,

permitting high speed and to supply coded current of a secondcode to therails of the section under traffic conditions requiring a restrictedspeed, and means associated with the track sec,- tion in the rear ofsaid track hazard to modify the operation of the coding means when atrain enters thatsection under the highspeed traflic conditions tosupply current of the second code forat least one short definite periodprior to supplying current of the first code.

6. In combination, a stretch of railway track including a permanenttrack hazard formed into insulated track sections, coding meansoperative at times to supply coded current of a first code to the railsof a section under traffic conditions permitting highv speedand tosupply coded current

